let x = undefined;
let y = undefined;
if (x === "") {
    let a = x;
}
if (x !== "") {
    let b = x;
}
if (x == "") {
    let c = x;
}
if (x != "") {
    let d = x;
}
if (x) {
    let e = x;
}
if (!x) {
    let f = x;
}
if (!!x) {
    let g = x;
}
if (!!!x) {
    let h = x;
}
